IAQ and COVID-19 Risk Mitigation in the Office Environment

After months working remotely, a recent survey of 2,300 U.S. workers revealed that more than 80 percent of the respondents would prefer to be back in the office for at least part of the work week. To make this a reality, building owners and their tenants need to have comprehensive return-to-work strategies in place to minimize the risk of spreading COVID-19 in the workplace. Indoor air quality will be a key area of focus as employers determine when, who and how to safely welcome people back to the office.

In general, experts agree that targeting between 3 (the bare minimum) to 5 (excellent) air changes per hour (ACH) is an important step toward keeping building occupants healthy during the pandemic and beyond.

One of the simplest ways to prevent the spread of harmful viruses indoors is to increase the amount of outdoor air delivered to that space. At home, this can be as easy as cracking a window or propping open the front door. But there’s far more to consider in a commercial office building.

To start with, many office buildings are designed to prevent people from opening windows. A tightly sealed building is more energy efficient. Facility managers can consider increasing the volume of outdoor air in the building by opening the dampers in the HVAC system. But that, too, has an impact on energy consumption. The more outdoor air that’s pumped into the building, the more energy is needed to condition the air.

In certain conditions, increasing outdoor air isn’t an option because of poor outside air quality. This was the situation during the recent wildfires in the Western U.S. While those fires burned, building owners needed to protect people by preventing the smoke-filled air from entering the buildings.

Building owners and facility managers have alternative strategies to consider. They should ensure the minimum outdoor air ventilation as per ASHRAE 62.1 and install MERV-13 or higher efficiency filters on the HVAC system to clean recirculated air. Buildings that can’t upgrade to at least MERV-13 filters to safely clean the recirculated air should supplement with in-room HEPA air cleaners. High-efficiency filtration can be as effective and lower cost than ventilation. Sized appropriately for the space, local air cleaners can effectively boost the ACH to ranges that achieve the target of 3-5 ACH.

In-room HEPA air cleaners can be part of a comprehensive COVID-19 risk mitigation strategy now and a long term solution to reduce the risk of airborne viruses and other harmful pathogens for years to come.

As companies consider their various re-entry strategies, enVerid, in collaboration with Dr. Marwa Zaatari, P.E., recently introduced a free tool to calculate energy, costs and carbon impact of various HVAC strategies for COVID-19 risk mitigation. The free, open-source enVerid COVID-19 Energy Estimator allows building owners, mechanical engineers, and facility managers to quickly gain a more complete picture of the risks, cost and carbon impacts of different ventilation and filtration approaches.